Electric switching device



1944- F. c. DOUGHMAN EI'AL 2,360,356

ELECTRIC SWITCHING DEVICE Filed June 4, 1942 a Sheets-Sheet 2 .4 M I a 6 4 8 1 U m 0 4 .7 50 w 2 86 1/ 1 0 F H 1 4 0 M? M ,o M

Oct. F. c. DOUGHMAN EFAL ELECTRIC SWITCHING DEVICE 5 Sheets-Sheet 3 Filed June 4 1942 NQ g Patented Oct. 24, 1944 ELECTRIC SWITCHING DEVICE Fer-man C. Doughman and Eric C. Wahlberg,

Stamford, Conn., assignors to Electrolux Corporation, New York, N. Y., a corporation of Dela- Application June 4, 1942, Serial No. 445,696

11 Claims. (01. 2041-97) Our invention relates to an improved electric switching device, and more particularly to a switch having a plurality of positions and in cluding means for automatically retaining the switch in at least one of such positions. for a comparatively short though appreciable length of time.

More speciiically, our invention relates to a snap-action switch having two terminal positions and an intermediate position. A switch of this nature includes means for rapidly throwing the switch from one terminal position to the other when a switch handle is actuated. In accordance with our invention means are provided for automatically interrupting in an intermediate position the throw of the switch which has been initiated by actuating the handle. The switch is held in this intermediate position for a short interval and is then automatically released to continue to travel to the other terminal position without further manipulation by the operator.

While a switch having these general characteristics may find wide application in the electrical art, the particular switch herein shown and described is especially suited for controlling in a simple manner the operation of the system in-' cluding a plurality of electric motors as shown and described in co-pending application Serial No. 428,018 filed January 24, 1942, by Eric C.

Wahlberg.

Further objects and advantages of our invention will be apparent from the following description considered in connection with the accompanying drawings, which form a part of this specification and of which: 7

Fig. 1 is an elevational view of a switching device in accordance with our invention;

Fig. 2 is a cross-sectional view on an enlarged scale of the device shown in Fig. 1;

Fig. 3 is a cross-sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is a cross-sectional perspective view on a still larger scale of a portion of the device illustrated in the preceding figures;

Fig. 5 is a view of a portion of the apparatus ner of connecting a switch in accordance with our invention in an electrical system.

Referring more particularly to Figs. 1 to 5, reference character. 10 designates generally a snapaction switch which is secured b means of a.

bracket l2 to the casing of a time-delay solenoid device l4.

Switch in includes a frame or chassis l6 on which is mounted a composite block of insulating material l8 formed with an arcuate surface 20. Mounted in grooves in the face of the block is a plurality of electric contact members 22, 24, 26, 26, 30, 32, 34 and 36 provided with binding screws or other suitable terminals for the connection thereto of conductors. All of these contacts are provided with arcuate track surfaces which conform to the curvature of the surface of the block l8, but are so arranged withl respect to the surface that they will be contacted by suitable metal rollers, as will appear hereinafter.

Contacts 22 and 24, constituting one set, are

' disposed close to each other in the same groove illustrated in Fig. 2,'but showing certain of the I certain parts in different positions; and

Fig. 9 is a wiring diagram illustrating the man- 50 as to be bridged by one roller. These contacts are of equal length and the arcuate tracks thereof extend from one end of the arcuate surface 20 on the insulating block to a short distance beyond the center of the surface 20.

Contacts 26 and 28 are located in alignment with each other, but separatedby a portion of the insulating block i8. These two contacts are placed closely adjacent to the contact 30 and in the same groove. This latter contact is of the same length as the contacts 22 or 24, whereas the contact '26 ends short of the center of the block, while the contact 28 is located at the center and extends a short distance on either side thereof. The relative location ofthe contacts 26, 28 and 30, which constitute another set, is such that a roller may bridge contacts 26 and 30, or contacts 28 and 30, depending upon the position of the roller.

Contacts 32, 34 and 36, constituting a third set,

are arranged in the same manner as contacts 26, 28 and 30.

Pivotally mounted on the switch frame i6 at 38 is a switch-actuating handle 40. The inner end of this handle is provided with a pin 42 which extends through a slot 44 formed in a switch arm 46. One end of a coil spring 48 bears against the pin 42, while the opposite end of the spring is anchored to the switch arm 46. The opposite end of the arm is formed as a blade 50 of insulating material, as is best seen in Fig. 4. This blade carries three metal rollers 52 which i will stop the latter in an intermediate position with the rollers bridging contacts 22 and 2d, 28

and 30, and 34 and 36, respectively.

Member 56 is formed with an arm 60 which extends at substantially right angles to the rest of the member. The free end of this arm is provided with a slot 62 through which extends a spindle 64 of the time-delay device 54. This spindle is threaded and provided with lock nuts t6 above and below the arm 60, the nuts being spaced sufficiently so as to permit pivoting of the arm with respect to the spindle when the latter is moved up and down. The upper end of the spindle is secured to the central portion of a diaphragm 68, the outer edge of which is clamped between a body member I and a lower head it. The lower surface of the body member "it is recessed so as to form, together with the diaphragm, a diaphragm chamber 73.

The upper surface of the body member ill is likewise recessed and a diaphragm id is clamped between the upper edge of the body and a ring it bolted thereto, so as to form an expansion chamber I8. A coil spring at is disposed between the body member and the diaphragm M. The body member If! is formed with a passageway 82 connecting diaphragm chamber it with expansion chamber 18. The rate of flow of fluid through this passageway may be controlled by means of a needle valve 84 adjustable from the exterior of the body III by means of a knurled knob 86.

Chambers I3 and I8 are also connected by means of a passageway 38 wh1ch is normally closed by a check valve 90 which is held against an annular seat 92 by means of a spring 94. A

member 96 is disposed between the valve disc til and the lower surface of the body member l0.

One end of the member 96 engages the edge of the disc, while an intermediate portion bears against the surface of member Iii. The opposite end of the member 96 extends downwardly. as is shown at 98, so as to be contacted by the diaphragm 68 after the latter has been raised a certain amount. When the diaphragm strikes the projection 98 it pivots the member 96 about its point of contact withthe member I0 as a fulcrum, thus moving the other end of the member 96 downwardly so as to tilt the valve disc 00 away from its seat 92.

' The body member and associated parts are supported by legs I00 above a casing I02, to which the bracket I2 is connected. An electromagnet coil I04 is mounted within the casing. An armature member I00 is slidably positioned on the spindle 64 and normally rests against a lower stop I08. A coil spring H0 is disposed between the upper end of the armature member and a nut II2 which has threaded engagement with the upper end of the spindle. An annular member H4 is secured within a circular opening formed in the top of casing I02 and is provided with a ring of resilient material II6 located at the inner end of a vonical recess formed in the lower face of member H4. The upper end of armature I06 is conical and is adapted to seat against the ring I I6 in the recess.

In Fig. 9 there is shown a wiring diagram of an electrical system embodying the above-described switching mechanism. The system includes a plurality of direct-current motors including field poles I20 and H2 and armature coils I24. Each armature coil is connected to the segments or a commutator I26 by means of the usual taps I28. In addition, each armature includes three slip rings I30, H2 and H4 which are connected to the armature winding at spaced points by means of taps ltd, I38 and I40. Brushes I412, H44 and M6 are associated with the slip rings, corresponding brushes of the different motors being connected together by means of conductors E46, I50 and H2.

The field coils of the separate motors are connected in series by means of conductors IN and 956, the field coil of the right-hand motor being connected to ground by means of conductor I50, while the field coil of the left-hand motor is connected to the contact 22 of the switch I E! by means of a conductor N60. The contact 24 of the switch is connected to one side of a suitable supply of excitation current by means of a conductor 862, the other side of the supply circuit being grounded. Each motor is provided with a pair of commutator brushes ltd and I65 connected in parallel to conductors Ebb and I70, respectively. Conductor Hit 15 connected to contact 32 of the switch, while conductor H0 is connected to contact 26. Contact 38 is connected by means of a conductor l W to one side of a suitable source of armature current, the other side of the circuit being grounded, and contact 30 is connected to ground by means of a conductor H4.

Conductor 6 5b is connected to contact 28, while conductor 652 is connected to contact 34. Conductors Hi? and lit connect conductors d and B52, and hence contacts 28 and 34, respectively, with the solenoidcoil m4 of the time-delay device id.

The above-described switching mechanism, when connected in the circuit illustrated in Fig. 9, operates as follows. It is assumed that the switch is in the position illustrated in Figs. 1 and 2, which is the position designated I in Fig. 9. In this position the rollers 52 are beyond all of the contacts and consequently all of the circuits through the switch are open and the motors are stationary. When it is desired to start the motors, the switch handle 48 is pivoted in a clockwise direction, as viewed in Figs. 1 and 2. This straightens out the toggle formed by the switch handle and the member 46, the spring 48 being compressed. After the switch handle has been pivoted a certain distance, the spring 48 causes the switch arm 46 to he suddenly thrown toward its other extreme position, as is characteristic of snap-action switches. However, the throw of the switch is interrupted at a midpoint by the blade 50 striking the projections 50 and the switch is stopped in the midpoint designated by II in Fig. 9. However, the spring 48 still tends to throw the switch to the extreme position designated by III.

In the position II one of the rollers bridges the contacts 22 and 24, thus closing the field circuit and supplying excitation current to the coils of the poles I20 and I22. Another of the rollers bridges the contacts 28 and 30, while the third roller bridges the contacts 34 and 36. Armature current is thus-supplied from the conductors I12 and I14 to the conductors I50 and I52 and hence through the brushes I44 and I48, the slip rings I32 and I30, and the taps I38 and I38 to the armature windings I24 01' each motor. As explained in detail in the above-mentioned application Serial No. 428,018, there is thus established relatively fixed magnetic poles in the armatures. Inasmuch as the field coils are excited, each armature is turned through the necessary angle to bring it into a fixed angular position with respect to the field and consequently the several armatures are brought into fixed angular position with respect to each other.

At the same time that current is supplied to the conductors I50 and I52, it is also supplied through the conductors I16 and I18 to the solenoid coil I04. Energization of this coil causes the armature I to be immediately moved upwardly until it contacts the resilient ring 8. The air contained within the diaphragm chamber 88 resists upward movement of the diaphragm, and consequently the spring I I0 is compressed. This spring tends to move the diaphragm upwardly and the air in the diaphragm chamber 13 is forced to flow through the passage 82 and past the needle valve 84 to within the expansion chamber 18. As this occurs the dia phragm moves slowly upwardly until it strikes the projection 88 on the member 98. Further movement of the diaphragm causes the member 85 to pivot so as to tilt the valve 80 away from the annular seat 82, thus establishing a substantially unobstructed path for flow of air through the passage 88 to the expansion chamber, which permits the diaphragm to be moved suddently upwardly. This movement of the diaphragm and the spindle 84 connected thereto, causes the member 55 to pivot in a clockwise direction, thus withdrawing the projections 58 from engagement with the blade 50 of the switch, whereupon the spring 48 causes the switch member 48 and blade 50 to resume its travel to the position III. The length of time during which the switch is held in the intermediate position 11 depends on the adjustment of the needle valve 84, and this valve is adjusted to hold the switch in the intermediate position long enough' for the armatures to be turned into angular alignment. In the position III the contacts 22 and 24 are still bridged by one of the rollers and conse- The contacts 22 and 24 are still bridged and the case if it were necessary for the air to flow past the needle valve 84. I As the diaphragm re turns to its lower position, the member 55 is pivoted in a counterclockwise direction so as to bring the projections 58 into the path of. travel of the blade 50.

When it is desired to stop the motors, the switch handle 40 is pivoted in a counterclockwise direction, thereby causing the switch arm 46 to travel from the position 111 toward the position I. The blade strikes the underside of the projections 58 and is held in this intermediate position in the same .manner as above described.

consequently excitation in the field coils is maintained. Contacts 28 and 30 and contacts 34 and 35 are now bridged, and consequently direct current is supplied to the conductors I50 and I52. This establishes relatively fixed magnetic poles in the armatures, as previously described, with the result that all of the armatures are brought to rest in angular alignment, as is described more in detail in the above-mentioned application Serial No. 428,018.

quently excitation current is still supplied to the field windings. However, in this position contacts 25 and 30 and contacts 32 and 35 are bridged, thus supplying armature current through the conductors I68 and I10 to the brushes I84 and I85 of the several motors. This causes the motors to operate in the normal manner. Due to the three-phase connection through the conductors I48, I and I52 between the several motors, they are caused to operate in synchronism. v

The switch is left in the position III as long as operation of the motors is desired. With the switch in this position, the circuit of the solenoid coil I04 is open and consequently armature I08 drops against the stop I08 on the spindle 6,4 and the weight of the armature tends to return the diaphragm 88 to the position shown in Fig. 2. This reduces the pressure of the diaphragm chamber 13 and the spring 84 permits the valve 30 to open under the influence of the higher pressure existing in the expansion chamber 18. In this'way, the diaphragm is returned to its lower position much more rapidly than would be In this position of the switch the solenoid coil I04 is energized and the action of the time- 'delay device I4 is the same as above described.

Consequently, after a short interval of'time the.

projections 58 are withdrawn from engagement with the blade 50, whereupon the switch arm, under the influence of spring 48, continues to the position I, where all circuits through the switch are open and the motors are at rest.

The positions 11 and IV, as shown in Fig, 9, are electrically the same, but mechanically they differ in that the blade 50 is on opposite sides of the projections 58. Thus, when the switch is thrown from the position illustrated in Fig: 2 (position I of Fig. 9) it strikes the upper side of the projections. Consequently, the force ofspring 48, which tends to move the switch, downwardly, also tends to pivot the member 56 in a clockwise direction, and hence the force of this spring aids the spring H0 in withdrawing the projections 58 from engagement with the blade. However, when the switch is thrown from the lower position in Fig. 2 (position III of Fig. 9) the blade 50 strikes the lower side of projections 58 and consequently the spring 48 tendsto turn the member 58 in a counterclockwise direction. Therefore, it resists the tendency of spring IIO to withdraw the projections 58 from engagement with the blade. Consequently, the switch will be held in the position IV for a greater length of time than in the position II. Ordinarily this is not objectionable, inasmuch as the switch oc- 'cupies the position IV when the motors are being stopped and a slight additional delay is not harmiul. On the contrary it may even be advantageous inasmuch as under some conditions a longer period is required to stop the motors than is required to initially align the armatures.

However, if the difference in the length of time during which the switch occupies the positions II and IV, respectively, is found to be objectionable, the switch illustrated in Figs. 6 through 8 may be employed. The switch here shown is the same as that previously described, with the exception of the pivoted member 56 and the projections 58. As will be seen from Figs. 6 through 8, a member I80 is pivoted at 54 and is provided v path of travel of the blade 50. These projections do not extend at exactly 90 from the member I80, as was the case in the previously described embodiment, but the upper angle between the member I80 and the projections, as viewed in Fig. 7, is slightly greater than 90. A member I84 is pivotally secured to the switch frame at I85 and extends above the lower end of member I80. As more particularly shown in Fig. 6, members I80 and I84 do not overlap laterally, but each is provided with cutawa portions for accommodating the forked end of the other. Member I84 is provided near its upper end with brackets I86 which embrace .pins I88 extending laterally from the lower end of member I80. Member I84 carries projections I98 disposed beside the projections I82 and forming a lower angle, as viewed in Fig. 7, of slightly more than 90".

With the switch in the position shown in Fig. 7, both the projections I82 and I90 are disposed in the path of travel of the blade 50. As the blade moves downwardly from the position shown it strikes the projections I80 carried by the pivoted member I84, inasmuch as the inner ends of projections I80 are slightly above the inner ends of projections I82. The force of the spring I 48 tends to pivot the member I84 in a clockwise direction about the point I85 and consequently tends to hold the projections I90 in engagement with the blade 50.

On the other hand, when the switch is thrown from thelower position he blade strikes the projections I82 carried by the member I80 and the force of the spring 48 tends to pivot this member in a counterclockwise direction about the point 54 and consequently tends to retain the projections I82 in engagement with the blade. In other words, the force of the spring 48 in both cases acts the same on the projections which are contacted by the blade and therefore the switch will be retained in the intermediate position for the same length of time, regardless of whether the switch is'being thrown from the position I toward the position III or vice versa.

When the switch is in the intermediate position, the solenoid of the time-delay device I4 is energized, as previously described, and after a short interval the spindle B4 is raised. This causes the member I80 to be pivoted in a clockwise direction Which in turn causes the member I84 to be pivoted in a counterclockwise direction by virtue of the pins I88 engaged by the brackets I86. Consequently, both projections I82 and I90 are Withdrawn from the path of travel of the switch blade.

While we have shown and described two more or less specific embodiments of our invention, it

' is to be understood that this has been done for purposes of illustration only and that the scope of our invention is not to be limited thereby, but is to be determined by the appended claims. Moreover, while we have shown our improved switching mechanism connected in a particular circuit, this has been done merely to illustrate one advantageous use of the device. Obviously, a switch in accordance with the invention may be employed in other circuits, either with the contacts as shown or arranged in other manners according to the requirements of the particular circuits.

What we claim is:

1. In a switch having two extreme positions and an intermediate position, means capable of being conditioned to throw said switch from either extreme position to the other extreme position, a member movable to condition said means, and means for interrupting the throw of the switch from either extreme position to the other and for retaining the switch for an appreciable period in the intermediate position.

2. In a switch, a movable switch arm having two extreme positions and an intermediate position, means capable of being conditioned to throw said arm from either extreme position to the other, a member movable to condition said means, structure normally positioned in the path of travel of said arm for interrupting the throw from either extreme position in said intermediate position, and means for clearing said structure from engagement with said arm after the latter has been retained in said intermediate position for an appreciable length of time.

3. In a switch, a movable switch am having two extreme positions and an intermediate position, means capable of being conditioned to throw said arm from either extreme position to the other, a member movable to condition said means, structure normally positioned in the path of travel of said arm for interrupting the throw from either extreme position in said intermediate position, an electric circuit connected so as to be closed by said arm in said intermediate position, means actuated by the closing of said circuit tending to release said structure from engagement with said arm, and means for delaying the release for an appreciable length of time.

4. In a switch, a movable switch arm having two extreme positions and an intermediate position, means capable of being conditioned to throw said arm from either extreme position to the other, a member movable to condition said means, structure normally positioned in the path of travel of said arm for interrupting the throw from either extreme position in said intermediate position, an electric circuit connected so as to be closed by said arm in said intermediate position, an electro. magnetic device connected in saidcircuit and actuated by the closing of the circuit so as to tend to release said structure from engagement withsaid arm, and dashpot means for delaying the release for an appreciable interval.

5. In an electric switching device, a snap-action switch including switch structure movable over a track between two terminal positions, means for moving said structure, a member normally positioned in the path of travel of said structure for arresting movement thereof from either terminal position in an intermediate position, contacts bridged by said structure when in said intermediate positlon, an electro-magnet connected to be energized by the bridging of said contacts, said electro-magnet including an armature, means connecting said armature to said member so as to tend to withdraw said member from said path of travel when the electro-magnet is energized, and means for delaying the withdrawal of said member.

6. In an electric switching device, a snap-action switch including an arcuate track, an arm carrying a contact roller movable over said track between two terminal positions, means for moving said arm, a pivotally mounted member, a projection carried by said member and normally positioned in the path of travel of said arm for arresting movement thereof in an intermediate position, contacts bridged by said roller when said arm is in said intermediate position, an electromagnet connected to be energized by the bridging of said contacts, an armature movable by said magnet, means connecting said pivotal member to said armature so as to tend to pivot said member to withdraw said projection from said path of travel when said magnet is energized, and means for delaying the pivoting of said member.

7. In an electric switching device, a snap-action switch including switch structure movable over a track between two terminal positions, a spring compressible to move said structure, a handle shiitable for compressing said spring, a member normally positioned in the path of travel of said structure for arresting movement thereof from either terminal position in an intermediate position with said spring still compressed, means actuated by the stopping of said structure in said intermediate position for withdrawing said member from said path of travel, whereby said spring may resume movement of said structure, and means tor delaying withdrawal of said member for an appreciable period.

8. In an electric switching device, a snapaction switch including switch structure movable over a track between two terminal positions, a spring compressible to move said structure, a handle shittable for compressing said spring, a

member normally positioned in the path of travel of said structure for arresting movement thereof in an intermediate position with said spring still compressed, contacts bridged by said structure when the latter is in said intermediate position, an electro-magnet connected to be energized by the bridging of said contacts, an armature movable by said magnet, means connecting said armature to said member so as to tend to withdraw the member from said path of travel, whereby said spring may resume movement of said structure, and'means for delaying withdrawal said member for an appreciable period.

9. In an electric switching device, a snap-action switch including switch structure movable in either direction over a track between two terminal positions, a spring compressible to move said structure, a handle shiitable for compressing said sprin a pair of members pivoted adjacent to opposite ends or said tract, a projection'carried by each of said members and normally positioned in the path oi travel or said structure for arresting movement thereof in an intermediate position with said spring still compressed, said struceling in one direction and contacting the other projection when traveling in the other direction, means actuated by the stopping of said structure in said intermediate position for pivoting said 5 members to withdraw both of said projections from withdrawal of said projections for an appreciable period.

10. In a switch having two extreme positions and an intermediate position, means capable of being conditioned to throw said switch from either extreme position to the other extreme position, a

' member movable to condition said means, means a means for moving said position, contact for interrupting the throw of the switch from either extreme position to the other and for retaining the switch for an appreciable period in the intermediate position, contact means arranged to bebridged only when said switch is in one of said'extreme positions, contact means arranged to be bridged only when said switch is in said intermediate position, and contact means arranged to be'bridged both when said switch is in said one of said extreme positions intermediate position.

11. In an electric switching device, a snapaction switch including switch structure movable over a track between two terminal positions,

structure, amember normally positioned in the path of travel of said structure for arresting movement thereof from either terminal position in an intermediate position, contact means arranged to be bridged only when said structure is in one of said extreme po-. sitions, contact means arranged to be bridged only when said structure is in said intermediate means arranged to be bridged both when said switch is in said one of said extreme positions and in said intermediate position, an electro-magnet connected to be energized when said second mentioned contact means are bridsedfsaid electro-masnet inclui nz an arms,- ture, means connecting said armature to said member so as to tend to withdraw said member tare contacting one of said projections when travis energized, and means drawal of said member.

from said path of travel when the electro-maznet C. DOUGHIMAN. ERIC C. WW.

and in said i'or delaying the with- 

